text: Suspensions of similarly charged particles dispersed in a liquid electrolyte are stabilized through an effect described by the Helmholtz double layer model. The model has two layers. The first layer is the charged surface of the particle, which creates an electrostatic field that affects the ions in the electrolyte. In response, the ions create a diffuse layer of equal and opposite charge, effectively rendering the surface charge neutral. However, the diffuse layer creates a potential surrounding the particle that differs from the bulk electrolyte.
  The diffuse layer serves as the long-range force for stabilization of the particles. When particles near one another, the diffuse layer of one particle overlaps with that of the other particle, generating a repulsive force. The following equation provides the energy between two colloids as a result of the Hamaker interactions and electrostatic repulsion.
  where:
  * , energy between a pair of colloids,
  * , radius of colloids,
  * , Hamaker constant between colloid and solvent,
  * , distance between colloids,
  * , surface ion concentration,
  * , Boltzmann constant,
  * , temperature in kelvins,
  *  surface excess,
  *  inverse Debye length.